Tasmania in February 2012: A record hot weekend

The last weekend of February was exceptionally hot in Tasmania, with maximum and minimum temperatures broken at some sites. Rainfall was below average in the south and northwest, but heavy rain saw above average rainfall in parts of the north.

A record hot weekend

The last weekend of February was very hot. Warm northerly winds and clear skies saw day-time temperatures reach up into the mid to high 30s on both the 25th and 26th, and night-time temperatures staying above 20 at some locations.

The 25th was the warmest day and Hobart Airport the warmest spot reaching 39.4 °C, its warmest February day in 30 years. Geeveston, Dover, Lake St Clair and Maydena all recording their highest February temperature on record that day. Maximum temperatures exceeded 36 °C on both days at several sites in the southeast. While this has happened a few times before, it is not common, and it is very unusual for so late in February.

Minimum temperatures were also very warm over that last weekend of February, with temperatures remaining above 20 °C at several locations. Maatsuyker Island, Orford, Geeveston, Devonport and Cape Grim all recorded their warmest February night (highest daily minimum temperature) on record that weekend, with Maatsuyker Island breaking its previous record by 3.1 °C. Hobart and Orford did not drop below 22 °C for two nights in a row, a first for Tasmania. Tasman Island recorded the highest minimum temperature for the month with 23.6 °C.

Record rain for Deal and Flinders Islands

A trough of low pressure over Bass Strait produced heavy rainfall over the Furneaux and Kent Islands on February 10 and 11. Daily rainfall totals ranged from 20 to 70 mm in the 24 hours to 9am on the 10th, but were heaviest with thunderstorms on the morning of the 11th. Deal Island recorded 114 mm in the 24 hours to 9am on the 11th, with Memana on Flinders Island recording 77 mm. For both locations, this is their highest February daily rainfall on record. The two-day rainfall totals for this period were also record-breaking, with Deal Island's 180 mm its wettest two-day period of any month. The previous wettest two-day period was 28 to 29 August 2001 when 140 mm was recorded.

As a result of the heavy rain on 10 and 11 February, both Deal Island and Memana recorded their highest total February rainfall on record. Deal Island's was also the wettest site in the state, with a total of 236 mm for the month.

Below average rainfall across the south, average in the north

Monthly rainfall totals were below average on King Island and across much of the southern half of Tasmania due to a lack of rain-bearing systems throughout the month. King Island Airport was the driest location, receiving only 8 mm for the month.

In the northern third of the state rainfall was close to average. Most of that rain was delivered during two events: on the 5th, moist northerly winds ahead of a cold front delivered daily falls of around 20 to 50 mm; and on the 17th showers and thunderstorms delivered falls of 20 to 60 mm to the central north. Deviot Jetty recorded 55 mm in 24 hours with this event, which is its wettest February day on record. Deviot Jetty had its wettest February on record as a result. In western and central areas, the wettest period was on the 5th and 6th as the cold front moved through, delivering daily totals of 20 to 70 mm.

Some cool weather, but warm days and nights overall

Overall, day-time temperatures were up to two degrees warmer than average, bolstered by the hot final weekend. There were a few cool days, mostly around the 1st, 6th to 10th and the 17th, when maximum temperatures generally remained below 20 °C. The coldest day was at Mount Wellington with 6.1 °C on the 8th.

There were many warm nights in February, with minimum temperatures averaging up to two degrees warmer than normal overall. There were some cool nights, mostly around the 1st, 7th to 13th and the 24th. The lowest temperature of the month was -0.3 °C at Liawenee on the 24th.

A very hot weekend in Hobart

The last weekend of February was a very hot one in Hobart. On Saturday the 25th the temperature reached 38.8 °C (the warmest February day since 1995) and on Sunday the 26th the temperature peaked at 36.0 °C. Two consecutive days over 36 °C have occurred just twice before in February (the last event was 14 to 15 February 1982), but never this late in the month. Minimum temperatures that weekend were also very warm: 22.2 °C overnight on Saturday and 23.4 °C overnight on Sunday night were the first time the temperature has remained above 22 °C over two consecutive nights. The overnight low of 23.4 °C was also the warmest February night since 4 February 1912 when 24.7 °C was recorded.

Overall, maximum temperatures in Hobart averaged at 22.5 °C and minimum temperatures at 13.3 °C, both close to one degree above average.

February rainfall of 23 mm was just over half the long-term average of 40 mm, which is less than the 54 mm recorded last year, and the lowest February total in Hobart since 2006 when 22 mm was recorded. Only a few cold fronts affected Tasmania in February, and those that did only delivered daily totals of less than 5 mm in Hobart. The wettest day was the 19th, when a cold front delivered 5 mm in 24 hours.

Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Tasmania using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at
9 am on Thursday 1 March 2012.
Some checks have been made on the data, but it is possible that results will change
as new information becomes available.

Averages are long-term means based on observations from
all available years of record, which vary widely from site to site.
They are not shown for sites with less than 10 years of record, as they cannot then be calculated reliably.
The median
is sometimes more representative than the
mean
of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
decile ranking
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a
percentage of the long-term mean.